LED illumination offers significant benefits over traditional lamp technologies including, but not limited to, longer illuminator lifetimes, more stable light output over illuminator lifetimes, ozone-free output, more precise lighting control, better thermal management to keep heat from the target object and lower cost.
Visible- and IR-wavelength LED lamps for machine vision applications are sometimes used in dusty and/or chemically reactive environments. Recently, UV LED lamps have found use as an alternative technology to traditional lamps for curing applications. Inks, adhesives, polymers and coatings are often cured using UV light for printing, manufacturing and 3D printing applications. In certain environments, a build-up of material can form on the outer (exit) window of the lamp over time, resulting in a reduction in the intensity of light emitted by the lamp. By way of example, in printing applications, ink can build up over time on the outer (exit) window of the lamp and cure on the outer surface of the outer (exit) window. By way of further example, in the lamps used in optical sorting systems, layers of dirt or dust can form on the outer (exit) window of the lamp, leading to a reduction in intensity of the light emitted by the lamp.
Users typically address these issues by shutting down their systems and scraping (i.e., manually removing) the built-up material from the outer (exit) window of the lamp. This solution is not ideal, inasmuch as such scraping of the outer (exit) window of the lamp often results in a permanently scratched outer (exit) window which can affect the optical output profile of the lamp. Another solution which is sometimes used by users is to remove the outer (exit) window from the lamp (which may require the entire lamp to be removed from a production line) and then immerse the outer (exit) window in a chemical solution to remove the built-up material. This chemical cleaning method can take up to an hour to complete for some materials, for example, inks which are fully cured on a surface of a glass window. In commercial environments where down-time of systems incorporating LED lamps needs to be minimized, it would be desirable to provide a secure, but easily replaceable, outer (exit) window to facilitate ease of removal and cleaning, or outright replacement, of the outer (exit) window. It would be preferable if the outer (exit) window did not require screws (or similar tool-installed fasteners) in order to be secured to the remainder of the lamp, and could be easily changed by non-technical personnel working without tools (e.g., screwdrivers, Allen wrenches and the like).
Machine vision and UV-curing applications are very sensitive to changes in light intensity and uniformity. In general, for machine vision applications, the brighter the light, the faster the machine vision system can operate, and the better the machine vision system will perform. In UV-curing applications, it is very important to maintain the intensity and uniformity of the light at the user's specifications in order to ensure that the material being cured is cured to the appropriate level. Furthermore, it is important to notify the user when the intensity and uniformity of the light varies from the user's specifications. For this reason, a sensor detecting excessive build-up of material on the outer (exit) window surface of the lamp would be very useful.
Therefore, it would be desirable to provide a replaceable window system on an LED lamp that can be easily removed by non-technical personnel, minimizing the down-time of the lamp and hence minimizing the down-time of the overall system employing the lamp, as well as sensors and software to manage the intensity, uniformity, thermal feedback and lifetime of the lamp, including detecting excessive build-up of material on the outer (exit) window surface of the lamp.